The present invention relates generally to the field of airplanes, and is particularly concerned with improvements in locking means for movable flight control surface members, such as rudders and the like, when parked.
Serious problems are encountered by airplanes, and particularly light airplanes, which are parked outside of hangers at airports, due to the effects of high winds as well as jet and propeller streams from neighboring aircraft. These wind effects are particularly disastrous in the case of the large surface flight control elements such as the rudder, and can not only result in damage to the parts themselves, but may readily have damaging effects on the control mechanisms, such as cables and the like.
Heretofore, it has been the practice in light planes particularly to utilize retaining straps or other expedients for clampingly retaining the control elements against movement. This is not only inconvenient but creates a hazard, in the event that these clamping elements are not removed prior to take-off.
This problem has been appreciated in the industry, and many arrangements have been suggested for locking and releasing the locked flight control elements by means of controls located in the cockpit, as exemplified by the above-noted prior art patents. In the main, the prior arrangements have been quite complicated arrangements and embody the use of components which must be built into the airplane at the time of its construction. Moreover, the arrangements did not as a rule include locking mechanisms which could be manually locked and unlocked by a ground attendant.
The locking mechanism as disclosed in U.S. Pat. No. 2,203,396 attempts to solve many of the inherent problems which are presented, but here, again, leaves much to be desired. While this patent does disclose a mechanism which can be operated by a ground attendant into locked and unlocked positions, and which is further arranged to be released by controls in the cockpit, the locking mechanism is such that it must of necessity be built into the airplane, and is not adapted to be installed as a unitized structure in airplanes which have already been built, and in which the locking mechanism is applied directly to the control element rather than indirectly as through a rudder controlling yoke as shown in U.S. Pat. No. 2,203,396.
The unitized locking mechanism of the present invention is such that it can be installed in existing planes and connected with existing cockpit controls to provide a fail-safe operation which will assure that the locking mechanism will be released prior to take-off, in the event that it has inadvertently been left in a locking position. Thus, the present invention enables an existing plane to be fitted with a locking mechanism particularly for the rudder element at a reasonable cost and with a minimum modification or change to the airplane existing structure. Moreover, the present invention discloses a structure which is contained within a closed portion of the plane so that it has no interference with the aerodynamics or surface structure of the plane.